The factory sprawls over an area larger than 20 soccer fields.
Inside, it’s brightly lit and filled with humming machinery, a mammoth
futuristic manufactory. Robot arms grab components from bins and place
each part with precision, while conveyor belts move the assembled pieces
smoothly down production lines. Finished products enter testing
stations for quality checks before being packed for shipping.

It has been called a gigafactory, and it does indeed produce
vast quantities of advanced batteries. But this gigafactory is in China,
not Nevada. It doesn’t make batteries for cars, and it’s not part of
the Elon Musk empire.

Opened in early 2017, in the northern Chinese port city of Dalian, this plant is owned by Rongke Power
and is turning out battery systems for some of the world’s largest
energy storage installations. It’s on target to produce 300 megawatts’
worth of batteries by the end of this year, eventually ramping up to 3
gigawatts per year.

The scale of this “other” gigafactory may be impressive, but
the core technology it makes is even more compelling. The Dalian factory
produces vanadium redox-flow batteries, a specialized type whose time
has finally come. The VRFB was invented decades ago but has emerged only
recently as one of the leading contenders for large-scale energy
storage.

How large? VRFBs are being touted for grid-scale uses in which
they would store up to hundreds of megawatt-hours of energy. In these
applications, they may be charged by large baseload power plants, which
generate electricity cheaply but are too sluggish to accommodate sharp
increases in demand during peak hours. Or they may be charged by
renewable sources like wind farms, whose generation doesn’t always align
well with demand. Like most batteries, VRFBs can deliver power nearly
instantaneously, so they can stand in for the traditional means of
meeting peak demand: fossil-fueled “peaker” plants that, in comparison
with batteries, are costly to maintain and operate and not as fast.
Lithium-ion batteries, too, have been proposed for grid-scale
uses. But here they are no match for VRFBs, which have longer lifetimes,
can be scaled up more easily, and can operate day in, day out, with no
significant performance loss for 20 years or more.

Soon this technology will be the cornerstone of the largest battery installation in the world: a ­200-MW, 800-megawatt-hour storage station being built in Dalian.
The first 100 MW will be installed by the end of this year, with the
remainder coming on line in 2018. The station will help balance supply
and demand on the Liaoning province power grid, which serves about 40
million people, filling the same function as a peaker power plant but
without using scarce water. Furthermore, if the batteries are charged by
the wind-generated power that’s abundant in northern China, no fossil
fuels will be burned. Should demand spike or the supply dip suddenly,
the battery station will be able to dispatch all or just part of its 200
MW within milliseconds.

The result will be a stable grid that can integrate more
renewable energy. At times, wind generation in Liaoning province tops 7
GW, or about 15 percent of total generation. But much of that power
isn’t used because other sources already meet grid demand. Earlier this
year, the amount of wind power in Liao­ning that was curtailed, or
wasted, reached 15 percent; in the neighboring province of Jilin, it was
30 percent. The Dalian site will store that wasted energy for later
use, adding up to a few hundred gigawatt-hours per month.

The Dalian site is just one of several big VRFB installations
being built in China, so its reign as the world’s biggest battery may be
short. Meanwhile, other countries are adopting VRFBs. According to the U.S. Department of Energy’s global energy storage database,
since 2014, more than 30 VRFB projects in 11 countries have been
deployed or begun construction; these range in power from a few tens of
kilowatts up to Dalian’s 200 MW. While these projects reflect the
surging interest in all forms of energy storage, what’s driving the
renewed push toward VRFBs are important technological distinctions.

Today’s state-of-the-art vanadium redox-flow batteries started out as a modest research project at the Pacific Northwest National Laboratory
(PNNL), a U.S. Department of Energy lab in Washington state. The PNNL
team, which I led, came together in 2007, at a time when world oil
prices were steadily climbing. The economies of China and India were
experiencing double-digit growth, and environmentalists were concerned
about the accelerating rate at which they (and other countries) were
consuming fossil fuels. In the United States, awareness was starting to
build about the potential of renewable but intermittent energy sources
like wind and solar.

This Battery Flows

The positive and negative sides of a
vanadium redox-flow battery are separated by a membrane that selectively
allows protons to go through. During charging, an applied voltage
causes vanadium ions to each lose an electron on the positive side. The
freed electrons flow through the outside circuit to the negative side,
where they are stored. During discharging, the stored electrons are
released, flowing back through the outside circuit to the positive side...

Against that backdrop, we decided to search for a better way
to store renewable energy as a means of promoting its adoption while
also improving grid reliability. Our group included the lab’s top
experts on power, materials, and chemistry, as well as an
­intellectual-property lawyer, Peter Christiansen, who has a background
in power engineering. Peter helped focus our efforts on technologies
that would have the greatest societal impact. In 2009, our group began
receiving significant support from the DOE’s Energy Storage Program, which boosted our annual R&D budget to US $10 million.....MORE